I just completely disassembled and reassembled my Dell Studio 1555 laptop. I had to remove the hard drive, WLAN card, unplug optical drive, display connector, even the motherboard to get to the fan.

I replaced the fan with a brand new fan, and everything seems to be working fine because I'm using the computer right now to type this. However, I want to check that the fan is functioning correctly because I don't hear it running and the fan speed isn't showing up when using sensors from the terminal.

Is there a way that I can be assured that the fan is functioning, e.g. get a fan speed when sensors is only showing temp1 and temp2?

The critical temp for both CPUs is 100 degrees Celsius and I'm at 54 and 46, so I'll have to power down soon if I can't figure this out.